**Christianity: Overview, Beliefs, and Historical Impact**

### Definition and Core Beliefs

Christianity is a monotheistic religion based on the life and teachings of Jesus Christ, who is the central figure in its doctrines. It is the world's largest religion with approximately 2.4 billion adherents, known as Christians. Christianity teaches that Jesus is the Son of God, sent to earth to save humanity from sin and its consequences. Central to its theology are beliefs in the incarnation, passion, crucifixion, resurrection, and ascension of Jesus, all of which affirm his role as the Savior and the path to eternal life.

### Origins and Historical Development

Christianity began in the 1st century AD as a Jewish sect in the Eastern Mediterranean, rapidly evolving and spreading across the Roman Empire and beyond. Jesus's disciples and their followers spread his teachings, leading to the establishment of communities that worshipped Jesus as the Messiah. By the 4th century, under Emperor Constantine the Great, Christianity was granted legal status, which dramatically accelerated its growth throughout the Roman Empire.

The Council of Nicaea in 325 AD was a pivotal moment in articulating the theological foundation of the Christian faith, leading to the formulation of the Nicene Creed, which remains a touchstone of Christian orthodoxy.

### Major Denominations

Christianity comprises various denominations with differing practices and theological interpretations but united in the core belief in Jesus Christ. The largest branches are:

1. **Roman Catholic Church**: The largest single Christian body, characterized by an episcopal hierarchy with the Pope at its head, and doctrines defined by ecumenical councils.
  
2. **Eastern Orthodox Church**: Known for its continuation of the original Christian traditions and practices along with its belief in the concept of deification (theosis) and the centrality of icons in worship.

3. **Protestantism**: Emerged in the 16th century during the Reformation, which protested against certain practices of the Catholic Church. It encompasses numerous denominations like Baptists, Methodists, Lutherans, Presbyterians, and Anglicans, each with their distinct practices but fundamentally adhering to the scripture's authority.

### Practices and Worship

Christian worship involves the commemoration of Jesus' life, his teachings, and his sacrificial death and resurrection. Common practices across most denominations include prayer, Bible reading, partaking in the sacraments (such as Baptism and Eucharist), and congregational worship services. Worship styles vary from solemn liturgies including chant in Orthodox churches to the enthusiastic services seen in many evangelical congregations.

### Ethical Values

Christian ethics, derived from the Bible and the teachings of Jesus, emphasize love, mercy, and forgiveness. The ethical teachings of Jesus include the Sermon on the Mount, which advocates for humility, compassion, and purity of heart. Christians are also called to social justice, guided by the principle of love for neighbors and the stewardship of God's creation.

### Global Influence

The cultural, social, humanitarian, and political impact of Christianity has been profound and multifaceted. It has inspired art, music, literature, law, and ethics; fostered the development of Western civilization; been a critical factor in political and social movements; and played a dynamic role in shaping global attitudes towards peace, justice, and human rights.

### Challenges and Contemporary Issues

Today, Christianity faces numerous challenges including secularization, moral relativism, and internal divisions along doctrinal lines. Additionally, global Christian communities often confront religious persecution in various parts of the world, impacting their freedom to worship and practice their religion openly.

### Conclusion

Christianity's foundational belief in Jesus as the Messiah and its rich theological, cultural, and historical traditions continue to play a crucial role in the lives of millions around the world. Despite contemporary challenges, it remains a potent force in personal spirituality, community building, and ethical leadership in the global context.